Grinding-mill.



P. D. GIDDINGS.

GRINDING MILL.

APPLICATION IILED JUNE 10, 1913.

1,131,230,, Patented Mar.9,1915.

Z7 28 Z7 Z8 3 5 lift @TATEh PATENT FRANK D. GIDDINGS, 015 FORT COLLINES, COLORADO.

GRINDING-MILL To all whom it may concern Be it known that l, FRANK D. GIDDINGs, a citizen of the United States, residing at Fort Collins, in the county of Larimer and State of Colorado, have invented certain new and useful Improvements in Grinding- Mills, of which the following is a specifica tion.

My invention relates to improvements in grinding mills and more particularly to mills of the type shown and described in my application for Patent No. 733,846, filed November 27, 1912.

In the mill disclosed in the application above referred to, a cylindrical grinding element is rotatably mounted inside a correspondingly shaped concave and the two elements are provided with toothed cutter bars, the teeth of which are formed and arranged to pass through each others interdental spaces.

The concave is provided with means for the automatic ejection of rocks and other obstructive objects, whereby to prevent possible breakage and interference with the operation of the mill, and while the cutter bars on the rotary element are reverslble, those on the concave have been shown to be provided with teeth along one of their edges only.

It is the primary object of the present invention to eliminate the above mentioned means for the ejection of obstructions from the concave and to prevent breakage of parts of the mill when obstructive objects enter the space between the grinding element and the concave of the same, by making the cutter bars on the latter, bendable so that when a solid object is moved through the said space by the action of the rotary element, the bars on the concave will bend to clear the passage for the said object, which subsequently is discharged from the concave together with the product of the mill.

The cutter bars on the concave are preferably composed of a plurality of alined sec tions which are separately removably attached thereto and which being made of mild steel, are rendered bendable by weakening a portion intermediate of its longitudinal edges. Sections thus constructed'bend without breaking by the impact of an obstructive object impelled through the grinding space by the action of the rotary element of the mill, and they can be repeatedly Patented Mar.. 9, 1915..

Serial No. 772,816.

straightened without being heated so that after an obstructive object has passed through the concave, the mill may be restored to its operative condition in a short period.

Another object of my invention resides in providing the cutter bars of the concave with teeth at their opposite longitudinal edges and by mounting said bars so that they may be reversed in case the teeth on their inner edges are worn or broken.

An embodiment of my invention has been illustrated in the accompanying drawings in the various views of which like parts are similarly designated, and in which,

Figure 1 represents a transverse, vertical section through the grinding element of my improved mill, Fig. 2, a vertical, longitudinal section through the same taken along a line 22, Fig. 1. Fig. 3, a perspective view of one of the sections of the cutter bars con nected with the rotary element of the mill, Fig. i, a similar view of a section of one of the reversible and bendable cutter bars comprised in the concave in which said rotary element has its movement, and Fig. 5, a perspective view of one of the last-mentioned sections showing a modified method of constructing the same.

Referring more specifically to the drawings, the reference character 2 designates the rotary grinding element of the mill, 3 the relatively stationary concave in which said element is concentrically moimted, 4 an endless belt conveyer which in practice carries the material to be ground into the space between the elements 2 and 3, and 5 an endless belt which moves in close proximity to the upper surface of the conveyer and extends obliquely rearwardly with relation to the direction in which said surface moves, for the purpose of providing a positive means for impelling thematerial carried on the conveyer into the mouth 6 of the concave.

The reference character 7 designates a roller which engages the upper surface of the conveyer to crush the leaves and stalks of the hay carried thereon, and to exclude to a certain extent, rocks and other obstructive objects from the concave; 8 des ignates a chute through which the product of the mill is conducted to a suitable conveyer or receptacle, and 10 is a scraper which engages the surface of the belt 4 as it moves around the drum at its forward end, for the purpose of 11 removing adherent matter from the said surface, which matter when dislodged from the scraper, falls into a bag 12 formed of a piece of cloth or other suitable material which is attached at its longitudinal edges to the scraper and to an angle bar at the upper edge, of the above-mentioned chute. A bar 13 which has a concave flange 14 to partially surround the roller 7, is disposed to form the upper edge of the mouth 6 of the concave intowhich the material carried on the co'nveyer is fed, the lower edge of the said mouth being determined by the upper edge of'the chute which thus provides a division between the said mouth and the discharge opening 15' of; the concave. The lower edge of the bar 13 at its rearward concave side is sharpened as at 16 to provide a -scraper which by engagement with the circiimferential surface of the roller 7 removes adherent matter therefrom. Gear's are arranged as shown, for the operation of the roller and the endless belt in conjunction with the conveye'r and other members of the machine which not forming part of the present invention, have been omitted from the drawings. I

The rotary element 2 of the grinding mill consists of a cyl-ii'ider composed of a plurality of adjoining sections 17 which are monnted upon a shaft 18 and held in place by means of \vashers 19 and nuts 20 which engage the outermost sections, the shaft having been provided at its end portions with le ft and right hand screw threads for thea pplication of the nuts.

Each of the cylinder sections has a number of equidistant, radially extending wings 21 reinforced by ribs and provided with holes for the reception of the bolts 'by '1ireans of which the cutter bars 22 are rigidly secured thereto. These bars are *composed of sections which in length equal the width of the cylinder sect-ions, and which, as best shown in Fig. 3 of the drawings, are formed at their longitudinal edges with truncated l' shaped teeth whose edges are sharpened to disintegrate the hiaterial fed into the mill. The spaces between the teeth are ni'ade of similar shape for the passage of the correspon'din'g'ly formed teeth on the cutter bars of the concave which will hereinafter be more run-y described.

The several Sections of which the cylinder is composed are preferably arranged on the shaft so that the cutter-bars secured to the corresponding wings of the same are disposed in staggered order in lines which W ind spirally along the circumferential surface of the cylinder.

The shaft 18 is supported in boxes 23 mounted upon the side hars'24; of the frame on which the various "parts of the machine are assembled, and it'carries a pul1ey'34: for its eperatrve comiedtion with the shaft of a traction engine or other conveniently located motor.

The rotary grinding element is partially inclosed at its upper and forward sides by the concave 3 which is formed of a number of sections secured at their extremities upon two annular heads 25 which are disposed beyond the ends of the cylinder 28 and rigidly secured to the before-mentioned side bars 2+1 of the supporting frame of the mill.

The lowermost section at the forward side of the concave, consists of a plate 26 which by means of a punching press has been formed with a multiplicity of integral, inwardly extending teeth; the next concave sections are composed of angle bars 27 which on their radially extending flanges, carry the cutter-bars 28 which hereinafter will be more fully described, and the remaining portion of the concave at the rearward side thereof is composed of a sheet metal cover 29 which is rigidly secured upon the beforementioned bar 13.

In addition to the cutter bars secured to the angle-bars 27, the concave is provided at the edges of its mouth, with two similarly constructed cutter bars 30 and 31 which are respectively secured to the angle bar at the upper edge of the chute 8 and in a recess in the lower surface of the bar 18.

The several cutter bars of the concave are each composed of a plurality of ali'ned sections which are made of mild steel and tempered along their edges in which the teeth are formed. The cutter bar sections are weakened along lines intermediate of their longitudinal toothed edges by a series of apertures 32 to facilitate their being bent along said lines, and they are furthermore provided at opposite sides of said lines with holes 33 for the reception of the bolts by means of which they are separately removably attached to the respective parts of the concave.

The teeth which are formed along the opposite longitudinal edges of the bar-sections, are shaped in correspondence with the interden'tal spaces of the cutter-bars on the rotary element above described, and the spaces between them are made of similar form to correspond with the teeth of the bars 22 which in the operation -'of "the mill, pass through them.

I desire it understood that the medial portions of the cutter bars at which they are bendable may be weakened by means other than the row of apertures 32, as forexample, by indenting the metal along a central longitudinal line, as is shown in Fig. '5 of the drawings.

The cutter bars carried on the rotary cylinder are made of heavier material than those on the concave and they are preferably composed of hardened steel to insure their rigidity and to compel them to resist strains due to the passage of obstructive solid articles through the grinding space of the mill.

The material when discharged over the forward end of the belt conveyer is engaged by the cutter-bars on the rotating cylinder and carried in the direction of the arrow a, through the grinding space between the circumferential surface of the cylinder and the inner surface of the concave, in which it is reduced to a meal by the passage of the teeth of the cutter bars between those of the bars which project inwardly from the concave sections, and those which are formed on the plate 26.

In case a rock or other obstructive object enters the mouth of the concave together with the hay discharged from the conveyor, it is carried upwardly by the cutter bars on the rotary cylinder until it encounters the first one of the bendable stationary cutterbars at the upper edge of said mouth, one or more sections of which are in consequence bent at their weakened portions to clear the passage for the obstruction into the grinding space. The other cutter bars of the concave are in a like manner bent one after the other and the obstructive object is subsequently discharged into the chute without having caused any other damage than the bending of a few of the sections of the cutter-bars which after having been removed, are easily straightened by placing them in a cold state upon a flat surface with their concave side downward and striking their opposite side with a hammer.

"When the teeth of any one of the cutterbar sections of either of the two elements of the mill become worn or broken, the said sections are readily reversed and the period during which the mill can be operated without resharpening the cutting edges of the teeth is consequently doubled.

The shape of the teeth as shown and described, minimizes the danger of breakage and it will be understood that by moving the cutter bars of the concave inward, wear of the teeth of the bars may be taken up, it be- Uopies of this patent may be obtained for five cents each, by addressing the ing obvious that this adjustment of the bars may be accomplished by providing the angle bars with oblong bolt holes as indicated in the drawings, or by other suitable methods.

Having thus described my invention what I claim and desire to secure by Letters-Patent is:

1. In a grinding mill, a concave having inwardly projecting cutter-bars, each composed of a plurality of separately reversible sections provided with teeth along their opposite, longitudinal edges, and a rotary grinding element having cutter-bars composed of separately reversible sections provided with teeth along their opposite longitudinal edges, the bars on the said element being arranged so that the teeth on one of their said edges will pass between those on the corresponding edges of the bars on the concave.

2. In a grinding mill, a concave comprising a cylindrical casing and radially inwardly projecting cutter bars each composed of a plurality of alined, individually reversible sections, provided with teeth along opposite edges, and a grinding element rotatable in said concave and having radially outwardly projecting cutter-bars each composed of a plurality of alined, individually reversible sections provided with teeth along opposite edges.

3. In a grinding mill of the character described, a normally rigid cutter bar bendable along a line determined by a series of aper tures.

4:. In a grinding mill, a cutter bar capable of resisting the stress to which it is subjected in the ordinary operation of the mill and having a weakened portion to permit of its bending under excessive stress, along a line substantially parallel to its cutting ed e.

' In testimony whereof I have affixed my signature in presence of two witnesses.

FRANK D. GIDDINGS. Witnesses:

W. F. NEIGHBORS, C. A. Forum.

Commissioner of Patents,

Washington, JD. 0. 

